Flame detector



March 4, 1958 J. A. DEUBEL FLAME DETECTOR Original Filed Sept. 20, 1950 2 Sheets-Sheet 1 rrofA/Eys.

J. DEUBEL FLAME DETECTOR March 4, 1958 2 Sheets-Sheet Original Filed Sept. 20. 1950 FJ@ i United States Patent O FLAME DETECTOR Justin A. Deubel, Milwaukee, Wis., assiguor to General Controls Co., Glendale, Calif., a corporation of California Continuation of application Serial No. 276,253, March 13, 1952, which is a division of application Serial No. 185,797, September 20, 1950, now Patent No. 2,660,645, dated November 24, 1953. This application April 17, 1956, Serial No. 578,714

15 Claims. (Cl. ZOO-138) This invention relates to a control mechanism that serves to open and close an associated electric circuit in accordance with external conditions which influence the operating mechanism. The present application is a continuation of my application, Serial No. 276,253, filed March 13, 1952, which is a division of application, Serial No. 185,797, now U. S. Patent 2,660,645.

More particularly, this invention concerns a novel type of switch that operates in response to temperature changes which has application as a flame responsive switch in an oil burner control apparatus.

In oil burner operation it is of prime importance to provide suicient and adequate safety devices to prevent burner operation under abnormal conditions. One f these safety requirements necessitates the use of a control that will stop burner operation upon failure to initiate combustion. Generally some type of llame responsive device has in the past been used to determine the presence or absence of llame, and these devices are usually located remotely from the burner and burner primary control. However, many of these devices now in use are subject to limitations in rapidity of response and length of useful life. Many factors contribute to cause these limitations but the most important one is the necessity of positioning the llame responsive device in proximity to the flame. The deteriorating effects of the llame, the temperature and pressure of the air stream, Vibration, etc. require a construction that will be relatively unaffected by these factors. This invention embodies a type of construction that effectively shields the moving parts from the llame and products of combustion, provides positive and immediate response to reversals in temperature change, and permits ease of adjustment and repair, and islocated within the burner blast tube and therefore can be assembled with the burner and primary control as a unit.

Further features will become apparent as this description proceeds and will be particularly pointed out in` the responsive switch with a portion of the side plate removed.

Figure 2 represents a top view of the flame vor heat responsive switch with a portion of the top plate removed. Figure 3 represents a top view of the'switch mounting.

Figure 4 represents an end view of the switch mounting. r

'Figure 5 represents a perspective view of the end portionl of an oil burner tube assembly with'the'flame detector mounted in a preferred location.

Figure 6 represents a perspective View of the assemf bracket 32 with a prong similar to the prong 10 and an bled switch and mounting. v ,l

lFigure 7 represents a front view of the switch contact fork'. f

Figure 8 is a View, similar to Figure'l, showing a modification of the device of Figure l. I' J .-lInrespect to comparativesizes in the several figures,

adjustable.

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the Figures 1, 2, 3, 4, 6, 7 and 8 are drawn to approxi-v mately twice the actual size.

Referring now to Figures 1 and 2 in which is shown the llame or heat responsive switch unit 10 having a casing 11 substantially rectangular in shape, encompassing the side, top and bottom with the ends left open. A rectangular cup-shaped closure member 12 is securely fastened within the open end of casing 11. The member 12 has an open end 13 and a closed end 14 sealing oit1 the opening 13 from the remainder of casing 11. The member 12 is formed of metal or other heat conductive material and is the primary recipient of heat radiation from the flame. A heat responsive member comprising a bimetallic strip l5, serving as an actuating member, is secured by welding or other suitable means to the closed end 14. This arrangement places the bimetal 15 in heat conductive relationship with the cup member 12. ln this arrangement, the free end 20 of bimetal 15 is securely fastened to a channelled lever 16. The lower ends 17 of the anges of channel-shaped lever 16 are perforated to receive a pivot pin 18 secured in position by lock rings 19. A channel-shaped contact lever 21 is similarly supported on the pivot pin 18 but separated from lever 16 by friction washers such as carbon washers 22. A flexible contact blade 33a is fastened by any suitable means to the web portion of lever 2l. Circumferentially surrounding the pin 18 and interposed between the anges of contact lever 21 is a compression spring 24. The spring 24 serves to spread the channel anges against the carbon washers 22 which are confined by the ends 17 and lock rings 19. The result of this arrangement permits unitary movement of levers 16 and 21 when such movement is unobstructed and also provides for slip frictional movement between levers 16 and 21 when the movement of lever 21 is obstructed.

Within the open end 25 of casing 11 is securely fastened an insulation piece 26 which effectively' seals this end of casing 11. Fastened to the piece 26 by rivets or other suitable means is an L-shaped, electrically conductive bracket 27. A contact prong 28 is secured to the bracket 27 and projects through a Ihole in insulation piece 26. A threaded aperture in the bracket 27 serves as a means of support and adjustment for a threaded contact member 29. A stop 31, supported by a bracket 32 which is riveted to the piece 26, limits the counter-v clockwise movement of lever 21. The contact 29 cooperates with the web-portion 33 of channel 21 to constitute a switch which may be integrated into the oil burner control system. Flexible blade 33a has a slight upward bias and therefore there is a small clearance beA tween blade 33a and the portion 33 when the contacts are open, the blade 33a being iiexed slightly downward when the contacts are closed. The amount of this pressback exure of blade 33a determines the magnitude of the temperature increase necessary to open the contacts. The position of contact 29 with relation to the Stop 3l is This adjustment determines the amount of unobstructed clockwise movement of lever 21 which may take place upon a decrease in temperature of the strip 15 and consequently determines the magnitude of the temn perature decrease necessary to `reclose the switch con-l tacts 29-33. As shown in the drawings, the stop 31 is exterior connection to complete a circuit. The contact' The device would then act as a double throw switch.

An up-turned portion of the contact lever 21 provides" an electrical terminal -34 to which a' ilexibleconductor lead: 35 is soldered. or otherwise fastened. The lead`35 is passed. over thev spring 24, ledv along the base of channel 16 and fastened to the casing 11 by soldering. This arrangement electrically grounds the lever 21 to the casing: 11. to provide one pathl for currentflow froml the switch. Essentially a high resistance ground exists from lever 21', through: carbon washers 22, channel 16, bimetal 15,. cup member 21, and casing 11, but this path is undesirable for thisl application of the invention in that current through the bimetal will `generate heat and affect operation of the switch.

Referring now to Figures 3, 4, 6 and 7, there is shown the switch mounting 36, comprising a mounting socket 37 and a mounting clamp 38. The clamp 38 is threaded to provide a tightening screw 39 which enables the mounting 36 to be secured to an oil tube 54 as shown in Figure 5. The mounting socket 37, formed of conductive metal, has an open angcd top 41 allowing insertion of llame responsive switch unit into the mounting socket 3'7. An open end 42 of mounting socket 37 has inturned edges 43 and 44 which form a slotted receptacle in the casing end. An inner insulation piece 45, a contact fork or receptacle 46 (Figure 7), and an insulation piece 47 are assembled within this slotted portion, after which the edges 43 and 44 are squeezed together and bent over to secure this assembly within the mounting socket 37. The insulation pieces 45 and 47 are made the same size as the end of the mounting socket 37. The contact fork 46 (Figure 7) adjacent its ends 50a and 50b provides an opening into which the contact prong 28 may be inserted upon assembling of the detector 10 and mounting 36. An `L.shaped extension 4S of the fork 46 is attached to the central wire 49 of a metal sheathed conductor lead. This type of lead has the central hot wire separated from the grounded sheath 50 by insulation. The grounded sheath 54) is soldered to a projection 44a of edge 44 of mounting socket 37 (Figure 6). Thus, when the unit 10 is assembled Within the mounting socket 37, the wire 49 is electrically connected to the extension 43, fork 46, prong 28, bracket 27 and contact 29. The grounded sheath 50 is electrically connected to the projection 44a, mounting socket 37, casing 11, lead 35, terminal 34, and contact lever v21. Figure 6 shows the assembled ilame detector 51 with the unit 10 inserted into the mounting socket 37.

Referring now to Figure 5 in which is shown the blasttube portion of a gun type oil burner having the flame detector 51 mounted on the oil tube 54. The blast tube 52 has an opening 53 through which the atomized mixture of oil and air is expelled into the combustion chamber of an oil-tired furnace. The oil tube 54 is provided with an orifice 55 from which the oil under pressure is injected into the air stream which ows inside the tube 52. Typical means provided for ignition purposes are the electrodes 56 with their corresponding insulators 57.

Note, that the detector unit 51 is mounted on the oil tube 54 in such a position that the end 13 of cup member 12 is in proximity to the opening 53 to receive a maximum of radiated heat from the burner llame.

In operation, when the oil burner is shut down the strip will be in its cold position and portion 33 will be in electrical contact with the contact 29, as shown in Figure l. After the oil burner is placed in operation, heat from the llame will be radiated to the member 12, at its end 14. By conduction and radiation, heat will be transmitted to strip 15. Assuming the higher expansive side of the bimetal strip 15 is adjacent the member 12, the strip 15 willl flex away from member 12 at its free end as its temperature increases. Upon the initial movement of the free end of strip 15, the member 16 and lever 21 will move as a unit, pivoting lever 21 counterclockwise about the pin 18. This movement, depending on the amount of press-back of blade 33a, soon separates contacts 29-33 indicating to the burner control apparatus to whichthe flame detector is connected that combustion is taking place within the` furnace combustion-chamber.

Continued increase in temperature of strip 15 moves the lever 21 into engagement with the stop 31, which obstructs further counterclockwise movement of lever 21. Further movement of strip 15 produces slippage at the carbon washers 22.

After the burner has operated for the required period and the burner flame has been extinguished, the strip 15 `will cool causingv it to move its free end toward member 12. This movement will immediately result in lever 21 leaving the stop 31 and moving into engagement With Contact 29. This closure of contacts 29-33 indicates to the burner control apparatus that the burner llame has been extinguished and the combustion chamber is cooling. Further cooling of strip 15 will result in slippage at the carbon washers 22. Lever 21 will be held in a position such that an increase in temperature of strip 15 will immediately open the contacts 29-33.

Figure 8 shows a modication of the device previously described. In this modification, the switch is arranged so as to be closed when the bimetal strip (comparable to strip 15 ofV Figure l) is in its hot position. This form of the ame detector has the contact assembly and the heat responsive element hermetically sealed within an outer casing 137.

The switch unit is composed of a flame responsive housing 111 including a plate 126, formed of suitable electrical insulating material. Plate 126 has riveted to it a bracket 132 carrying a stop 131. An electrically conductive rivet 163 fastens a contact carrying bracket 127 to the plate 126. A contact carrying blade 12in is fastened by any suitable means to a channel-shaped lever 121, the lever 121 and a member 116 being assembled on a pin 118 by means of the slip-friction mechanism previously described. Member 116 is mounted on the free end of strip 115, which, in turn, is secured by any suitable means to a cup-shaped member 112. In assembling the ilame detector, the housing 111 including plate 126, upon. which are mounted brackets 127 and 132, is inserted into casing 137. Member 112 is then inserted into the casing 137 which, in turn, is inserted into a mounting socket 37 shown in Figure 4. The flanged edges of member 112 rest against the edges of casing 137, to which they may be soldered thereby hermetically sealing the assembly. The operation of the modication of Figure. 8 is identical to that previously described, except that the switch contacts are closed upon an increase in temperature and opened upon a decrease in temperature.

There has been illustrated preferred embodiments of the invention, but its scope is to be limited only by the appended claims.

What is claimed is:

l. Anapparatus for detecting the presence or absence of heat radiation comprising, a casing, a heat-conductive endwall in said casing having a front face adapted to be exposed to direct heat radiation, an actuating member movable in response to changes in temperature and mounted within said casing to receive heat by conduction from the rear face of said endwall, a iixed contact mounted within said casing, a movable Contact, stop means mounted on said casing in spaced relationship to said fixed Contact for arresting movement of said movable contact and pivoted slip-friction connecting means connecting said actuating member to said movable contact to thereby allow said actuating member to move independently of said movable contact either when said movable Contact engages said fixed contact or when the movement of said movable contact is arrested by said stop means.

2. An apparatus for detecting the presence or absence of heat radiation comprising, a casing, a heat conductive endwall in said casing having a front face adapted to be exposed to direct heat radiation, an actuating member within said casing and movable in response to changes in temperature, said member being mounted rigidly on 5 the rear face of said endwall to receive heat by conduction therefrom, a ixed contact mounted within said casing, a movable contact, stop means mounted on said casing in spaced relationship to said ixed contact for arresting movement of said movable contact and pivoted slip-friction connecting means connecting said actuating member to said movable contact to thereby allow said actuating member to move independently of said movable contact either when said movable Contact engages said xed contact or when the movement of said movable contact is arrested by said stop means.

3. An apparatus for detecting the presence or absence of heat radiation comprising, a casing, a heat conductive endwall in said casing having a front face adapted to be exposed to direct heat radiation, an actuating member enclosed within said casing and shielded by said endwall from direct heat radiation, said member being movable in response to changes in temperature and mounted rigidly in good heat conducting relation to the rear face of said endwall to receive heat by conduction therefrom, a fixed contact mounted within said casing, a movable contact, stop means mounted on said casing in spaced relationship to said xed contact for arresting movement of said movable contact and pivoted slip-friction connecting means connecting said actuating member to said movable contact to thereby allow said actuating member to move independently of said movable contact either when said movable contact engages said fixed contact or when the movement of said movable contact is arrested by said stop means.

4. An apparatus for detecting the presence or absence of heat radiation comprising, an elongated casing adapted to have one of its small ends exposed to direct heat radiation, a heat conductive endwall closing said one end and shielding the space enclosed by said casing from direct heat radiation, an actuating member within said casing and movable in response to changes in temperature, said member being mounted in good heat conducting relation with the rear face of said endwall to receive heat by conduction therefrom, a tixed contact mounted withiny said casing adjacent the other of its small ends, a movable contact adapted to cooperate with said fixed contact, a carrier arm for said movable contact, said arm having a pivotal connection with said actu ating member for transmitting movement of said member to said arm, and slip-friction means including means for loading said pivotal connection to resist relative movement between said actuating member and said carrier arm.

5. An apparatus for detecting the presence or absence of heat radiation comprising, a casing, a heat conductive endwall in said casing having a front face adapted to be exposed to direct heat radiation, an actuating member within said casing including a bimetal element having a free end movable in response to temperature changes, the other end of said element being rigidly secured in good heat conducting relation to the rear face of said endwall' and adapted to receive heat by conduction therefrom, a fixed contact mounted within said casing, a movable contact, stop means mounted on said casing in spaced relationship to said iixed contact for arresting movement of said movable contact and pivoted slip-friction connecting means connecting said actuating member to said movable contact to thereby allow said actuating member to move independently of said movable contact either when said movable contact engages said fixed contact or lwhen the movement of said movable contact is arrested by said stop means.

6. An apparatus for detecting the presence or absence of heat radiation comprising, a casing, a heat conductive endwall in said casing having a front face adapted to be exposed to direct heat radiation, an actuating member enclosed within said casing and shielded by said endwall from direct heat radiation, said member including an elongated bimetal element having one end rigidly secured in good heat conducting relation to the rea-r face of said to :said fixed contact for arresting movement of said mov-1 able contact and pivoted slip-friction connecting means connecting said actuating member to said movable contact to thereby allow said actuating member to move independently of said movable contact either when said movable Contact engages said fixed contact or when the movement of said movable contact is arrested by said stop means.

7. An apparatus for detecting the presence or absence of heat radiation comprising, an elongated casing adapted to have one of its small ends exposed to direct heat radiation, a heat conductive endwall closing said one end and shielding the space enclosed by said casing from direct heat radiation, an actuating member within said casing and movable in response to changes in temperature, said member including an elongated bimetal element having one end rigidly secured in good heat conducting relation to the rear face of said endwall to receive heat by conduction therefrom, a xed contact mounted within said casing adjacent the other of its small ends, a movable contact, stop means -mounted on said casing in spaced relationship to said ixed contact for arresting movement of said movable contact and pivoted slip-friction connecting means connecting said actuating member to said movable contact to `thereby allow said actuating member to move independently of said movable contact either Vwhen said movable contact engages said iixed contact or when the movement of said movable contact is arrested by said stop means.

8. An apparatus for detecting the presence or absence of heat radiation comprising, a casing, a heat conductive endwall in said casing having a front face adapted to be exposed to direct heat radiation, an actuating member within said casing including a bimetal element having a free end movable in response to temperature changes, the other -end of said element being rigidly secured in good heat conducting relation to the rear face of said endwall and adapted to receive heat by conduction therefrom, a `tixed contact mounted within said casing, an arm carrying a movable contact adapted to cooperate with said xed contact, a link member having one end rigidly secured to the free end of said bimetal element and adapted to be moved thereby, and pivotal connecting means between the other end of ysaid link member and said contactcarrying arm, said connecting means including slipfriction means for loading said connecting means to resist relative movement between said link member and said contact-carrying arm.

9. An apparatus for detecting the presence or absence of heat radiation comprising, a casing, a heat conductive endwall in said casing having a front face adapted to be exposed to direct heat radiation, an actuating member within said casing including a bimetal element having a i'ree end movable in response to temperature changes,

the other end of said element being rigidly secured in good heat conducting relation to the rear face of said endwall and adapted to receive heat by conduction therefrom, a fixed contact mounted within said casing, an arm carrying a movable contact adapted to cooperate with said fixed contact, a link member having one end rigidly secured to the free end of said bimetal element and adapted to be moved thereby, and pivotal connecting means between the other end of said link member and said contact-carrying arm, said connecting means including a pivot pin extending through adjacent portions of said link member and ysaid arm, a friction member having surfaces contiguous with said arm and said link member, and resilient means applying a force normal to said contiguous surfaces thereby providing a frictional force resisting relative movement of said arm and said link member.

agnes-vea l0. An apparatus; for` detecting the` presence or absence. of heat radiation comprising, ak casing,y a heatconductive endwall in said casing having a front face adapted to be exposed to direct heat radiation, an actuating member movable in response to changes: inr temperature and mounted within said casing to receive heat by conduction from the rear face of said endwall, a xed contact mounted within said casing, a. movable contact connected to said actuating member for engaging and disengaging With said fixed Contact upon movement of'said actuating member, said actuating member having a slip-friction connection with said movable contact for transmitting movement of said' member to said movable contact.

11. An. apparatus for detectingV the presence or absence of heat radiation comprising, a casing, a heatconductive endwall in said casing having a front face adapted to be exposed to direct heat radiation, an actuating member within said casing and movable in response to changes in temperature, said member being mounted rigidly on the rear face of said endwall to receivey heatv by conduction therefrom, a iixed contact mounted within said casing, a movable contactconnected to said actuating member for engagement and disengagement with said iixed contact upon movement ofi said actuatingl member, said actuating member having a slip-frictiony connection with said movable contact for transmitting movement of said member to said movable contact.

12. An apparatus for detecting the presence or absence of heat radiation comprising, a casing, a heatconductive endwall in said casing having a front face adapted to be exposed to direct heat radiation, an actuating member enclosed within said casing and shielded by said endwall from direct heat radiation, saidl member being movable in response to changes in temperature and mounted rigidly in good heat conducting relation to the rear face of said endwall to receive heat by conduction therefrom, a iixed contact mounted Within said casing,l a movable contact connected to said actuating member for engagement and disengagement with said fixed contact upon movement of said actuating member, said actuating member having a. slip-friction connection with said movable contact for transmitting movement of saidl member to said movable contact.

13. An apparatus for detecting the presence or absence of heat radiation comprising, a casing, a heatconductive endwall in said casing having a front face adapted to be exposed to direct heat radiation, an actuating member within said casing including a bimetal element having a free end movable in response to temperature changes, the other end of said element being rigidly secured in good heat conducting relation to the rear face of said endwall and .adapted to receive heat by conduction therefrom, a lixed contact mounted within said casing, a movable contact within said casing for engagement with said fixed contact, said actuatingy memer having a slip-friction connection with said movable contact, whereby movement or"l said actuating member moves saidV movable contact into and out of engagement with said fixed contact and over-travel of said actuating member in either direction will be compensated for by the slip-friction connection.

14. An apparatus for detecting the presence or absence of heat radiation comprising, a casing, a heatconductive endwall in said casing having a front face adapted: to be exposed to direct heat radiation,` an actuating member enclosed within said casing and shielded by said endwall from direct heat radiation, said member including an elongated bimetal element having one end rigidly secured in good heat conducting relation to the rear face of said endwall to receive heat by conduction therefrom and' having its other end movableV in two directions, a fixed contact mounted Within said casing, means carrying a movable contact within said casing, said actuating member having a slip-friction connectionl with said movable contact carrying means for transmitting movement of said member to said movable contact to engage said' lixed contact in one direction of travelof said bimetal element and to disengage from said fixed contact in the other direction of travel of said bimetal element.

15. An apparatus for detecting the presence or absence of heat radiation comprising, an elongated casing adapted to have one of its small ends exposed to direct heat radiation, a heat conductive endwall closing said one end and shielding the space enclosed by said casing fromy direct heat radiation, an actuating member within said casing and movable in response to changes in temperature, said member including an elongated bimetal element having one end rigidly secured in good heat conducting relation to the rear face 0f said endwall to re ceive heat by conduction therefrom, a fixed contact mounted Within said casing adjacent the other of its small ends, a movable contact adapted to cooperate with said xed contact to open and close an electrical circuit, a support for said movable contact, and slip-friction connecting means between said actuating member and said movable contact support for transmitting movement of said member to said support to move said movable contact into engagement with said fixed contact in one direction of travel or" said member and to move said movable contact out of engagement with said fixed contact in another direction of travel yof said member.

References Cited in the iile of this patent UNITED STATES PATENTS 2,152,843 Fisher Apr. 4, 1939 2,428,838 Derby Oct; 14, 1947 2,431,771 Rosche Dec. 2, 1947 2,512,331 Hughes `lune 20,4 1950' 2,600,692 Rothwell et al. June, 1,7,y 19,52 2,730,593 Frerer Jan. 10, 1956 

